Hi, Gang. I have a bone-stock 1971 GS 350. The manual calls for 4 degrees BTDC initial timing. I now see my actual initial timing has been set at 10 degrees BTDC (measured with vac. advance disconnected and correct idle RPM) ever since I've owned the car. It has started and run just fine with this additional advance for several years. My question: Should I be thinking about resetting the timing to the 4 degrees BTDC spec., or just continue to run the car as currently set at 10 degrees. By the way, the car doesn't seem to knock or heat up, with the current additonal initial advance setting. Thanks for any thoughts! John
John, Your question is typical of why I wrote my Power Timing thread. The only time your engine runs at initial timing is when it is at idle. The second you accelerate and RPM goes up, the mechanical and vacuum advance adds timing. That is why you are always better off setting the total timing, and letting the initial fall where it has to. The 1971 and 72 distributors fitted to the 350 engine only had about 16-18* of mechanical advance. This may have been done for emissions, but it sure hurts power. If your distributor is original, you can probably raise the initial timing even more. 32* total timing, will likely be the best total timing. Set that with the vacuum advance disconnected and plugged. Follow the instructions here: http://www.v8buick.com/showthread.php?t=63475
Thanks for the excellent help, Sean and Larry. By the way, Larry's prior posting that he gave the link for has super information about total timing advance. Best, John in Wisconsin
I have a 72 with 14* mechanical.. I run 20-22 initial.. Ported vacuum with 12* .. And it all seems to work just fine with 87 octane..
Nope.. THe other way around.. 20-22 initial.. 14 mechanical Hell. On the turbo car. The distributor is locked.. No mechanical.. I run 34* initial with 10* start retard.. Stalls at 2800, so as soon as I hit the gas I'm at 34* of timing.. As the boost comes on I pull 1/2* per pound.. I use a ported vacuum for another 9* at cruise.. Yes, it idles perfectly at 34* of timing.. Amazing what you can get away with when you have low compression..
One of the advantages of the 71-72 350 distributors. They have very little mechanical advance. They usually only have anywhere from 12-18*, so you can run a lot of initial advance, and a cammed motor may need that much.
